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icy, do you have any comment on exposure liability towards neighbors that sit higher than the roof level in the event of a major leak?

I wouldn't want one in my back yard.

However, codes are written based on many factors...all which boil down to what is considered as providing the public with a "reasonable" degree of safety. From what was presented in this article, I believe the risk from a few hundred pounds of R717 really isn't as big a deal as once thought.

However, codes are written based on many factors...all which boil down to what is considered as providing the public with a "reasonable" degree of safety. From what was presented in this article, I believe the risk from a few hundred pounds of R717 really isn't as big a deal as once thought.

Anhydrous Ammonia Info

Originally Posted by Iceneck

Just out of curiousity...if a rack lost 200lbs of NH3, how great a danger would that pose to people around the store? I know it's heavier than air, but have no perspective about how dangerous it would be.

First thing, Anhydrous Ammonia (R717 or Nh3) is not heavier than air. It is in fact lighter than air, the reason most videos show the Ammonia close to the ground is because Anhydrous Ammonia is very much attracted to moisture. Which is why your eyes and any cuts on your skin will burn when you come into contact with Ammonia. More times than not the ground will be wetter (hold more moisture) than the air, unless of course its raining, which is why we normally see Ammonia "hugging" the ground.

Secondly, back in 2009 in Cincinnati, OH/Northern KY there was an Ammonia Release at a dairy plant, they lost over 50,000 pounds of Ammonia, the entire city of Northern Kentucky was evacuated. Luckly for the city it was raining that day which made for a much "better" Ammonia Release. Anyhow I was one of the Hazmat Tech's (Also at the time was employed as an Ammonia Technician) that went into the building to shut the King Valve off that was accedentally opened. If it would not have been for the rain that day, the entire city could have potiently been wiped out. Ammonia Releases are VERY DANGEROUS. Even small ammounts under 100 pounds (Any Nh3 Release under 100 pounds does not have to be reported) have the potiental of severally injuring or even killing thousands of people, if the conditions are right for the situation (release in a populated enclosed area).

It is for these reasons that Ammonia Technicians require a ton of training and education.

As for bringing Ammonia into the Commercial Supermarket business, it is currently illegal to have Ammonia "flowing" into a public (populated) supermarket. With that being said, it is not however illegal to have a Refrigeration system with a secondary refrigerant such as CO2 or Glycol as the "main (primary)" refrigerant that is "flowing" inside the supermarket, and have the Ammonia (R717) as the secondary refrigerant helping cool the Glycol or CO2 on the outside of the building.

Now I hope that this doesnt turn away any potiental Nh3 Operators in the future. Being well trained and educated paired with being cautious, Ammonia Releases like the one mentioned above are rare due to good Maintanence and good Mechanics. Ammonia is a GREAT refrigerant with absolultly NO harmful effects to the Ozone layer, much more cost effective and all around (assuming you have a good understanding and respect for how an Ammonia Refrigeration System operates) better type of Refrigeration Systems (Boils at lower levels helping to achieve colder temperatures [0 degrees thru -88 degrees in a full vaccum]).

I have been an Ammonia Technician for most of my life and I wouldn't rather be doing anything else. I love what I do and I encourage any technician either on the fience about making the move to Ammonia or new to the business to not shy away from Ammonia. Read and learn about it. I am willing to answer any and all the questions I can to help any Nh3 Techs (Vets or Newbies) and any HVAC Techs with any information about how to get into the Ammonia field or tips on good schools for Ammonia Refrigeration.

I hope this helped You sir and the rest of the Tech's who viewed / commented on this thread to better understand the benifits and dangers of Anhydrous Ammonia as a Refrigerant.

Ammonia is the perfect refrigerant. Unfortunately, it will probably 20 years until the changeover is complete. The largest holdback, is that ammonia is cheap and readily available. All manufacturers despise that. Trust me, there will be a ton of ammonia to glycol systems .

It is for these reasons that Ammonia Technicians require a ton of training and education.

Flammability vs health hazard are trade offs between high purity HC and ammonia.
Ammonia has been in use along with methyl chloride and sulfur dioxide before CFCs. They're ALL safe if properly contained. Those have been phased out and didn't come back because of serious health hazard when they leak.
Ammonia is right up there in inhalation hazard.

Another concern is that it's a DEA list I precursor. They've figured out a way to dope fertilizer grade NH3 to prevent its illicit use, so that pushes them over to refrigeration equipment to source it illegally. The process of stealing can accompany a massive release which can call for a community evacuation.

As for bringing Ammonia into the Commercial Supermarket business, it is currently illegal to have Ammonia "flowing" into a public (populated) supermarket. With that being said, it is not however illegal to have a Refrigeration system with a secondary refrigerant such as CO2 or Glycol as the "main (primary)" refrigerant that is "flowing" inside the supermarket, and have the Ammonia (R717) as the secondary refrigerant helping cool the Glycol or CO2 on the outside of the building.

compared to? It's comparable to R22. Higher than R502. I don't know of any R22 or 404A systems that run below atmosphere.
In fact, current replacement for super cold application of R13B1(super ozone killer with ODP of TEN) is R410A.

Commercial refer: R-404A, 507 and 22 and some oddballs here and there. 0 ODP, 404 has very high GWP

Comfort cooling: HCFC-123... the only ODP currently allowed for new installs.. but this is a replacement for CFC-11 which operates with sub atmospheric pressure.

For systems using secondary loop system, I'm not sure if ammonia is safer than ventilated HC system. With an HC system, you have just got to make sure that leak is quickly ventilated to bring it below flammable limit.

I think corrosiveness, inhalation hazard.. and desirability to thieves that makes such release even more likely are big hurdles. The only setback for fluorocarbons today is global warming potential which I think is hocus pocus long term effect. Ammonia poses immediate danger to life and a massive exposure liability.